1. Field of the Invention
The invention relates to wireless telecommunication technologies, and in particular, to wireless telecommunication service testing.
2. Description of the Prior Art
In wireless telecommunication networks, mobile switching centers (MSCs) provide call control and switching for calls placed by wireless customers using wireless handsets. The wireless handsets communicate wirelessly with base stations, which in turn are coupled to MSCs over hardwired connections, such as T-1 lines. MSCs are commonly capable of terminating calls to other wireless customers, as well as to destinations on the public switched telephone network (PSTN).
Often times, it is desirable to test the performance of MSCs. One prior art solution for testing MSC performance is to use a wireless test set to dial a local test number. In such a case, the MSC routes the test call to a switch in the local exchange carrier (LEC) network. The switch terminates the call to a specialized port that provides audio feedback to allow an test engineer to determine the quality of the connection to the MSC. One drawback to this solution is that the LECs frequently change local test numbers without providing updates to wireless operators. Another drawback is that the LECs charge local access fees to the wireless operators when test calls are terminated to their networks.
One prior art solution to the problems associated with terminating test calls to LEC switches involves installing specialized tone cards in MSCs. FIG. 1 illustrates communication network 100 in an example of the prior art for performing wireless service testing. Communication network 100 includes test set 101, base station 105, MSC 110, and public switched telephone network 120. MSC 110 includes routing system 113, call control system 115, and tone card 114. FIG. 2 illustrates the operation of communication network 110 in a prior art example of service testing.
Referring to FIG. 2, a call is initiated by a test operator placing a call to a specialized telephone number. Call control system 113 processes the phone number using a group of database tables typically referred to as translation tables. The translation tables store routing information in association with phone numbers. Based on the routing information stored in association with the phone number for the tone card, call control system 113 directs routing system 112 to route the incoming call from test set 101 to tone card 114. Call setup is performed between test set 101 and call control system 113 to establish a call connection between test set 101 and tone card 114.
Once the test call is connected, tone card 114 provides tone to test set 101 to enable the test operator to check service quality. In this manner, wireless operators can maintain the test numbers themselves, rather than relying upon a LEC. This solution also eliminates the access charges incurred when terminating to a LEC.
In one problem, current tone cards only allow for testing for a limited amount of time, such as for 255 seconds. As a result, specialized processing elements of call control system 113 are typically programmed to monitor the duration of test calls to tone card 114 and end the calls at the expiration of a specific time period. Upon reaching the time limit, call control system 113 directs that a circuit busy signal be generated and provided to test set 101. Call control system 113 also directs that the call connection to tone card 114 be torn down. The operator must then redial the phone number if it is desired to continue testing.
Unfortunately, prior art tone cards are designed and manufactured by third parties and affecting a change in the design to allow for extended testing would therefore be impractical. In many cases, this time limit significantly hinders the ability of wireless operators to test MSC performance. For example, in such a small amount of time it is not possible for a test operator to move across multiple cells to test how well an MSC handles handoffs between base stations. The specialized processing elements of call control system 114 could be modified to eliminate or bypass the time limits that are set at the beginning of a test call. However, such modifications must be implemented by the MSC manufacturer in response to a request for feature by the wireless operators and are typically prohibitively expensive.